It is generally known to store user data in the form of records on a data storage medium for purposes of backing up the user data. An exemplary system for storing and retrieving such user data is shown in FIG. 1 at 10 and generally includes a host system 12, a data transfer processor 14, and a data storage medium 16.
Host system 12 is generally a computer having a processor and memory which is capable of running an application program that enables data to be read from and written to data storage medium 16. Data transfer processor 14 is typically coupled between host system 12 and data storage medium 16 and organizes and controls the flow of data therebetween. Data transfer processor 14 can include memory which enables data which is retrieved from data storage medium 16 to be temporarily stored until such a time when it is appropriate to transfer the data to host system 12.
It is customary to effect the transfer of data from data storage medium 16 to host system 12 by placing not only the data content of individual records into a temporary memory location or data buffer in data transfer processor 14, but also additional information such as the individual lengths of each of the records transferred into the data transfer processor from data storage medium 16. Accordingly, this additional information has to be managed, stored, and processed whenever a data transfer is effected. Thus, the transfer of data is not as simple as merely retrieving stored data from data storage medium 16 and routing it to host system 12. Needless to say, management and organization of such information results in a large overhead in addition to processing complexities. It is desirable to reduce the overhead required to handle such information as well as the processing complexities involved therewith.
Exemplary data transfer methods and systems, and in particular those pertaining to tape drive systems are described in the following patents, the disclosures of which are incorporated by reference herein: U.S. Pat. Nos. 5,586,280, 5,210,851, 5,361,176, 5,377,056, 5,274,508, 5,367,410, 5,363,253, and 5,412,516.
This invention arose out of concerns associated with providing improved methods and systems for transferring data between data storage mediums and host systems, and in particular between tape drives and host systems.